1. Field of the Invention
This invention generally relates to microvalves, and more specifically, to microvalves that are well suited for use in harsh environments.
2. Background Art
There are a number of situations in which valves are subjected to harsh environments. One such application is in rocket engines, where valves are used to direct exhaust gases to help steer the rocket. These valves are subjected to very harsh conditions, and specifically, to very high temperatures and pressures and to highly corrosive gases. In addition to being subjected to these extremely difficult conditions, it is critical that the valves operate precisely in order to accurately steer the rocket. In order to achieve the necessary operating precision, these valves are machined very precisely. Because of this needed highly precise mechanical machining, the valves are very expensive.
It would be desirable if these prior art mechanically machined valves could be replaced with microelectromechanical valves where critical features of the valves could be made using photolithographic procedures, which can achieve very high precision at a lower cost than mechanical machining. In order to achieve this, however, the valves need to be designed so that they can operate in a harsh environment and so that critical features of the valves can, in fact, be made using photolithography procedures.